Maryland prone to twisters but nothing like what Oklahoma saw Monday

In 1929, two people were killed when a powerful F3 tornado moved through Frederick and Keymar.

In 1979, a F2 twister ripped the roof off the Shriver Canning Factory buildings in Westminster.

In 1996, a F3 twister plowed through Gamber and damaged 67 homes.

Tornadoes can happen in Carroll. They can be destructive. Since 1893, more than $6 million in damage has been caused by twisters in the county, according to data provided by Carroll County Emergency Management.

But in more than 100 years of record keeping, an EF5 monster tornado similar to the one that killed 24 and flattened entire neighborhoods in Moore, Okla., Monday has not touched down in Carroll.

Since 1952, 340 tornadoes have touched down in Maryland, according to data from http://www.tornadohistoryproject.com. None of those were rated F5 or EF5 on the Fujita Scale or the Enhanced Fujita scale, respectively. F5 and EF5 storms are considered the strongest, and most dangerous, tornadoes.

Just two twisters since 1952 were rated F4, the second-highest rating. An F4 tornado ripped through Allegany County in 1998 and an F4 tornado ravaged La Plata in 2002.

When an F3 tornado blew through Gamber July 19, 1996, Christian and Ethan March, both toddlers, were in cribs on the second level of their home. The twister ripped that level off the house and deposited the children on the ground outside their home. They suffered only minor injuries.

Homeowners should have an emergency plan for tornadoes, Carroll County Emergency Management Coordinator Jim Weed said. Town houses can be damaged by EF2 and EF3 tornadoes, he said.

Heading to the basement and staying in a corner when tornado warnings are issued by the National Weather Service is advisable, he said.

"That's where you want to be," he said.

AccuWeather meteorologist Eric Leister said there are several factors that typically prevent significant tornadoes from forming in Maryland.

Among them:

Proximity to Atlantic Ocean: In the plains, warm air from the Gulf of Mexico flows northward. The moist air has high dew points. When the moist air clashes with cold air, instability can develop, leading to tornadoes.

"In the mid-Atlantic, it can get hot and humid but a lot of times our air masses are generated by the Atlantic Ocean, which isn't quite as warm as the Gulf of Mexico gets," Leister said.

Changes in geography: Often, storms have to traverse over hills and valleys before reaching Central Maryland.

"Here in the East, you have lots of hills and terrain to deal with that can help keep the tornadoes a little bit smaller and weaker," Leister said.

Proximity to the Appalachians: Being east of a major mountain chain helps. The mountains can break up the storms, a luxury those in the plains do not have with mostly flat terrain.

"The Appalachians help in terms of the air masses and the terrain," Leister said. "They are a protecting mechanism."

EF5 tornadoes are rare, even in areas of the Midwest and the Plains, where twisters are common. The Moore tornado was the first EF5 tornado registered since a late May outbreak in 2011, when storms ravaged Piedmont, Okla., and Joplin, Mo.

"From a percentage standpoint, since those areas have more thunderstorms, they are more likely to see more tornadoes and, therefore, more devastating tornadoes," Leister said.

Tornado shelters and warning sirens are prevalent in the plains. Residents in Oklahoma, Texas, Kansas and Missouri are used to tornado warnings being issued.

In the mid-Atlantic, tornadoes are usually much weaker and touch down only for a few miles before breaking up.

Thanks to a cooler-than-average spring, the risk of tornadoes is even smaller in the region, at least until a dramatic warm-up occurs, Leister said.

"If we get an air mass that comes in off the Atlantic Ocean, it is actually going to inhibit thunderstorms," he said. "If we aren't getting thunderstorms, we're certainly not going to get any tornadoes."